OFDM TX/RX with large packet_len size


I’ve problem to use a large packet_len size (ie; 1500 bytes) in OFDM
Flowgraph as in the digital folder examples. I got this error:

sched: <block ofdm_cyclic_prefixer (34)> is requesting more input data
than we can provide.
ninput_items_required = 34
max_possible_items_available = 31
If this is a filter, consider reducing the number of taps.

My setup is:

min output buffer in cyclic prefix=100000

Btw, if i’m using FFT=64, it does works fine when I increase the kernel
shmax value. I attached the GRC that i’m using. Please kindly advice for
this problem. My objective is to make this OFDM flowgraph to works with
UDP/TCP packets. Or maybe there is another workaround to implement this?

Another question, is this OFDM TX/RX example is working good for QAM16?
I’ve try this with my b200, it seems I got lots of packet lost when I’m
trying to transmit a file or some random source.